Left ventricular (LV) function is an important determinant of postoperative prognosis in patients with aortic regurgitation. Hence, to preserve LV function, aortic valve replacement has been recommended to many asymptomatic patients with normal LV function. However, the natural history of such patients is unknown. We therefore assessed the natural history of 79 asymptomatic patients with normal LV ejection fraction by radionuclide angiography. During mean follow up of 47 months, 11 patients underwent operation because of symptoms and a twelfth because of asymptomatic LV dysfunction. By life table analysis, 75% + 8% of patients did not require operation at 7 years. There were no deaths. In the operative patients, LV function improved postop. Since death is rare, less than 4%/year require operation because of symptoms or LV dysfunction, and LV function improves after operation, "prophylactic" valve replacement to preserve LV function is not required in asymptomatic patients with AR and normal LV function.